The group observed children interacting with iPads in over 60 studies. The results of analyzing that data have produced the "best practices" guide that's now freely available. Here's an example of what you'll find in the guide:

"Just as researchers have documented the 'formal features' of television, which are the rules, syntax, and indicators of audio and visuals cues designed to help children understand a television show, we are beginning to understand the formal features of touchscreen devices. We now know, for example, that hotspots (triggers that take children to new locations within the app) in the lower right- and left-hand corners of the screen are precisely where children rest their wrists, which inevitably means that children accidentally exited the activity they were in."